/*公共样式*/
*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
html,body{
    height: 100%;
}
/*导航栏样式*/
.nav{
    height: 5%;
    background-color: rgb(50,50,50);
    color: rgb(255,255,255);
/*弹性布局，垂直居中*/
    display: flex;
    align-items: center;
    /*让里面的元素理左边有一定距离*/
    padding-left: 20px;
}
